1. Field of the Invention
The invention relates to a material based on manganese-doped zinc silicate and, more particularly, to a phosphor material with a short decay time that can be applied notably in displays. The invention also relates to a method for the obtaining of this material.
2. Description of the Prior Art
Known phosphors include manganese-doped zinc silicate Zn.sub.2 SiO.sub.4 :Mn which has been known for several years under the trade name of P1. Under photon or electron excitation, P1 emits a highly saturated green light. Furthermore, its high luminous output, associated with its resistance to marking under the impact of the exciting beam, make it a choice phosphor for display. The P1 phosphor is much used in avionics for HUD or HDD (head-up display or head-down display) visors and in plasma panels.
The phosphors known to date have a manganese doping level lower than or equal to 3.5%. This doping level is represented by x in the general chemical formula: EQU Zn.sub.2-x Mn.sub.x SiO.sub.4
Phosphors of this type have been described in the document EP 123 947 as well as in the article by A. L. N. STEVELS et al, "Fine Structure in the Low Temperature Luminescence of Zn.sub.2 SiO.sub.4 :Mn and Mg.sub.4 Ta.sub.2 O.sub.9 :Mn" in Journal of Luminescence8 (1974) - 443-451. However, the materials described have only a low level of manganese doping. These materials have the advantage wherein, under excitation, they emit a green radiation that is very highly saturated, hence shows very high luminosity.
It has been noted that these materials have a substantial decay time (extinguishing time) that can go up to 25 ms, which is a drawback in certain display applications. However, it is preferred to keep a low level of manganese doping in order to be assured of obtaining high luminous output.